. This study proposes the use of electrospray to form monodisperse droplets of controlled size from drug containing aqueous solutions. The accurate control of droplet sizes and size distributions would increase the precision by which aerosol delivered drugs could be targeted to various parts of the respiratory tract. The configuration of airways and the size dependence of deposition mechanisms determine which particle sizes will selectively be deposited in a particular region of the respiratory tract. During the Phase I funding period, electrospray techniques will be developed to provide control over both droplet size and size distribution from the point of generation to the point of delivery through a transfer line. The relative merits of charged versus neutral droplets will be explored. Effects on the droplet size distribution of the delivery line will be measured for varying air flows and droplet charge states.